RELATED STORIES • Recurrent or chronic mononucleosis: Is there such a thing? INFECTIOUS DISEASE Viral Illnesses • Chickenpox • Mumps • Postherpetic neuralgia • Croup • Measles • Rubella • Mononucleosis • Smallpox • Parvovirus infection • West Nile virus • Roseola • Rabies • SARS • Viral hemorrhagic fevers • Polio • Hand-foot-and-mouth disease

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Infectious mononucleosis (mono), or glandular fever, is often called the kissing disease. The label is only partly true. The virus that causes this disease is transmitted through saliva, so kissing can spread the virus, but so can coughing, sneezing, or sharing a glass or food utensil. Mononucleosis isn't as contagious as some other infections, such as the common cold.

The cause of mononucleosis is the Epstein-Barr virus, although similar signs and symptoms are sometimes caused by cytomegalovirus (CMV). Full-blown mononucleosis is most common in adolescents and young adults. Young children usually have minimal symptoms, and the infection often goes unrecognized. In lesser developed countries, mononucleosis is more frequently acquired at a young age, so classic signs and symptoms of mononucleosis aren't as common as they are in developed nations.

Mononucleosis usually isn't very serious, although the virus remains in your body for life. Most people have been exposed to the Epstein-Barr virus by the time they're 35 years old and have built up antibodies. They're immune and won't get mononucleosis again. Treatment mostly involves bed rest and getting adequate fluids.

Signs and symptoms of mononucleosis may include:

• Fatigue
• Weakness
• Sore throat, perhaps a strep throat that doesn't get better with antibiotics
• Fever
• Swollen lymph nodes in your neck and armpits
• Swollen tonsils
• Headache
• Skin rash
• Loss of appetite
• Soft, swollen spleen
• Night sweats

In children between the ages of 4 and 15, the virus may cause a mild illness that resembles a common respiratory infection. In older adults, mononucleosis causes more severe signs and symptoms and lasts longer.

The virus typically has an incubation period of four to six weeks, although in young children this period is shorter. Signs and symptoms such as fever and sore throat usually lessen within a couple of weeks, although fatigue, enlarged lymph nodes and a swollen spleen may last for a few weeks longer.

If you've been feeling tired and weak; have had a persistent fever, headache, loss of appetite, rash and muscle aches; and have had swollen lymph nodes and tonsils — these are strong indications that you have mononucleosis. If rest and a healthy diet don't ease your symptoms within a week or two or if your symptoms recur, see your doctor.

Your doctor may suspect mononucleosis based on your signs and symptoms and a physical examination.

If there's a need for additional confirmation, a Monospot test may be done to check your blood for antibodies to the Epstein-Barr virus. This screening test gives results within a day. But it may not detect the infection during the first week of the illness. A different antibody blood test requires a longer result time, but can detect the disease even within the first week of symptoms.

Your doctor may use other blood tests to look for an elevated number of white blood cells (lymphocytes) or abnormal-looking lymphocytes. These blood tests won't confirm mononucleosis, but they may suggest it as a possibility.

Among significant complications of mononucleosis is enlargement of the spleen. In extreme cases, your spleen may rupture, causing sharp, sudden pain in the left side of your upper abdomen. If such pain occurs, seek medical attention immediately — you may need surgery.

Most people with mononucleosis have mild liver inflammation (hepatitis). A yellowing of your skin and the whites of your eyes (jaundice) occurs occasionally, usually in people older than 35. About half the people with mononucleosis have a low count of platelets, which are blood cells involved in clotting.

Less common complications
Mononucleosis can also result in the following less common complications:

• Anemia, a decrease in red blood cells and in hemoglobin, an iron-rich protein in red blood cells
• Inflammation of the heart
• Complications involving the nervous system (meningitis, encephalitis, seizures, Bell's palsy, Guillain-Barre syndrome)
• Swollen tonsils, leading to obstructed breathing

The Epstein-Barr virus can cause much more serious illness in people who have impaired immune systems, such as people with HIV/AIDS or people taking drugs to suppress immunity after an organ transplant.

There's no specific therapy available to treat infectious mononucleosis. Antibiotics don't work against viral infections such as mono. Treatment mainly involves bed rest and adequate fluid intake.

Occasionally, a streptococcal (strep) infection accompanies the sore throat of mononucleosis. You may also develop a sinus infection or an infection of your tonsils (tonsillitis). If so, you may need treatment with antibiotics for these accompanying bacterial infections.

Some people with mononucleosis who take ampicillin (Principen), amoxicillin (Amoxil, Trimox), or amoxicillin and clavulanate (Augmentin) antibiotics may develop a rash, but this doesn't mean that they're allergic to the antibiotic. If needed, other antibiotics that are less likely to cause a rash are available to treat infections that may accompany mononucleosis.

To ease some of your symptoms, such as swelling of your throat and tonsils, your doctor may prescribe a corticosteroid medication such as prednisone.

Mononucleosis is believed to spread through saliva. If you're infected, you can help prevent spreading the virus to others by not kissing them and by not sharing food, dishes, glasses and utensils until several days after your fever has subsided and even longer, if possible.

The Epstein-Barr virus may persist in your saliva for months after the infection. If you've had mononucleosis, don't donate blood for at least six months after the onset of the illness.

There's no vaccine to prevent mononucleosis.

In addition to getting plenty of bed rest, these steps can help relieve symptoms:

• Drink plenty of water and fruit juices. Fluids help relieve fever and sore throat and prevent dehydration.
• Take an over-the-counter pain reliever. Use pain relievers such as acetaminophen (Tylenol, others) or ibuprofen (Advil, Motrin, others) as needed. These medicines have no antiviral properties; the only reasons to take them are to relieve pain or a fever. Don't give aspirin to a child under age 16. Aspirin may trigger a rare but potentially fatal disorder known as Reye's syndrome.
• Gargle with salt water. Do this several times a day to relieve sore throat. Mix 1/2 teaspoon salt in a glass of warm water.

Most signs and symptoms of mononucleosis ease within a few weeks, but it may be two to three months before you feel completely normal. The more rest you get initially, the sooner you should recover.

Returning to your usual schedule too soon can increase the risk of a relapse. If you're an athlete, be cautious about returning to strenuous activities or contact sports, especially if your spleen is enlarged, because of the increased risk of rupturing the spleen.

Children with mononucleosis and an enlarged spleen shouldn't engage in vigorous activities, roughhousing or contact sports for the same reason. Rupture of the spleen results in severe bleeding and is a medical emergency. Doctors recommend avoiding contact sports for at least one to two months after you've had mononucleosis, depending on how long it takes your spleen to return to normal size.

Although you may not be able to return to vigorous activities right away, your doctor may recommend gradual exercise to help you rebuild your strength as you recover from mononucleosis.

Mononucleosis can be a prolonged condition, keeping you at home for weeks as you recover. But be patient with your body as it fights the infection.

For the first week, you may be so fatigued that you feel too weak to even get out of bed. But the tiredness lessens with time. Throat soreness is generally the worst for the first five to seven days of illness. Your swollen lymph glands (nodes) should return to normal size by the fourth week of infection.

For young people, having mononucleosis will mean some missed activities — classes, team practices and parties. Without doubt, you'll need to take it easy for a while.

If you have mononucleosis, you don't necessarily need to be quarantined. Many people are already immune to the Epstein-Barr virus that causes the disease because of prior exposure to the virus as a child. But plan on staying home from class and other activities until you're feeling better.

Seek the help of friends and family as you recover from mononucleosis. College students should also contact the campus student health center staff for assistance or treatment, if necessary.